An X-ray tube of this type is disclosed e.g. in German patent No. 2,448,497. For the supply of high voltage to the electrode arrangement of such a tube it is known e.g. from U.S. Pat. No. 4,789,997 to use a circuit arrangement comprising an alternating current source and a multi stage voltage multiplier e.g. of the Cockroft-Walton type.
For such high voltage tubes it is a general aim to improve the high voltage stability, reduce the structural volume and weight of the tube, in particular for mobile X-ray equipment and to operate the tube at increased high voltage levels.
The latter aim being as a matter of principle in conflict with the need to avoid excessive fields strengths, particularly in the region of the electrode. support, which may result in high voltage breakdown, it has been suggested to reduce this risk by incorporating an intermediate electrode formed by a metal sleeve arranged concentrically with respect to said outer and inner electrodes and dividing said annular insulating disc into two separate annular disc parts.